The technology exists for winding lengths of uncut magnetic core material into a partially assembled toroidal transformer. One such system is shown in U.S. Pat. No. 4,741,484 issued May 3, 1988, the disclosure of which is incorporated by reference. The process used is illustrated best in FIGS. 42 and 47 of the patent. This technology has been developed for use with rolls of uncut crystalline, grain oriented silicon steel typically about 0.18 to 0.30 mm thick.
Recently great advances have been made in amorphous (non-crystalline) magnetic alloys for use as the core material for transformers. These amorphous materials are substantially more efficient than the best silicon magnetic steel alloys. Amorphous transformer core materials can be purchased from Allied-Signal Corp. of Morristown. N. J.
Amorphous core material which is to be wound into a partially assembled toroidal transformer is commonly supplied to the user on very large rolls. The material on these large rolls is then wound onto spools by the user. The spools mimic the size of the bobbin within the partial transformer. After being so wound, the spools of amorphous material are subjected to an annealing operation to relieve bending stresses created by winding the amorphous material onto the smaller spools. Such annealing operations are necessary to ensure maximum magnetic efficiency.
One of the problems with amorphous magnetic core materials is that they may be quite thin, about 0.025 mm thick, which is only one-tenth the thickness of conventional silicon magnetic steel core material. The thinness makes handling the amorphous material more difficult than silicon steel. Also, the currently available amorphous magnetic alloys become brittle, as the result of stress relief annealing operations, which create further problems in handling.